Sequestrum

A sequestrum is a fragment of dead bone that has become separated from living bone, typically as a result of osteomyelitis or severely compromised blood supply during fracture healing. It is often surrounded by reactive new bone called an involucrum and may be associated with a draining tract or cloaca through which pus and necrotic tissue can exit.

Pathophysiology involves localized necrosis from diminished blood flow and infection. The detached necrotic fragment remains nonviable and may persist within the surrounding infected bone or be expelled over time. The presence of a sequestrum usually signals a chronic or established infection and can impede healing unless removed.

Clinical features depend on location but commonly include localized bone pain, tenderness, swelling, and sometimes drainage from a sinus or fistula. Fever and systemic symptoms may be present with acute osteomyelitis. Radiographic and cross-sectional imaging typically show a distinct radiopaque bone fragment within a lesion, often with surrounding sclerosis, periosteal reaction, or thickened involucrum. CT is useful for defining the sequestrum’s size and position; MRI can assess surrounding soft-tissue involvement.

Management centers on surgical removal of the sequestrum with thorough debridement of infected tissue, paired with appropriate antimicrobial therapy tailored to culture results. In chronic mandibular or facial osteomyelitis, careful reconstruction may be necessary after debridement. Prognosis improves with complete removal and control of infection, though persistent necrosis or extensive infection can complicate recovery.

Etymology: sequestrum derives from Latin for “a thing separated,” reflecting the dead bone that has become detached from living tissue.